(function () {
  // 获取元素
const elevator = document.querySelector('.xtx-elevator');
const backTop = document.querySelector('#backTop');

window.addEventListener('scroll', function () {
  const n = document.documentElement.scrollTop
  n>=300?elevator.style.opacity=1:elevator.style.opacity=0
});

backTop.addEventListener('click', function () {
  window.scrollTo(0, 0)
});
})();

(function () {
  // 获取元素
  const elevator = document.querySelector('.xtx-elevator');
  const newGoods = document.querySelector('.xtx_goods_new');
  const popular = document.querySelector('.xtx_goods_popular');
  const brand = document.querySelector('.xtx_goods_brand');
  const topic = document.querySelector('.xtx_goods_topic');

  // 绑定事件委托
  elevator.addEventListener('click', function (e) {
    if (e.target.tagName === 'A' && e.target.dataset.name) { 
      // 获取自定义属性
      const goodsName = e.target.dataset.name
      switch (goodsName) {
        case 'newGoods':
          window.scrollTo(0, newGoods.offsetTop)
          break;
          case 'popular':
            window.scrollTo(0, popular.offsetTop)
          break;
          case 'brand':
            window.scrollTo(0, brand.offsetTop)
          break;
          case 'topic':
            window.scrollTo(0, topic.offsetTop)
          break;
        default:
          alert('出BUG了')
       }
    }
  });

  // 绑定滚动事件
  window.addEventListener('scroll', function () {
    const n = document.documentElement.scrollTop
    // console.log(n);
    elevator.querySelector('a.active') && elevator.querySelector('a.active').classList.remove('active')
    if (n >= newGoods.offsetTop && n < popular.offsetTop) {
      elevator.querySelector('a[data-name="newGoods"]').classList.add('active');
    } else if (n >= popular.offsetTop && n < brand.offsetTop) {
      elevator.querySelector('a[data-name="popular"]').classList.add('active');
    } else if(n >= brand.offsetTop && n < topic.offsetTop){ 
      elevator.querySelector('a[data-name="brand"]').classList.add('active');
    }else if(n >= topic.offsetTop ){ 
      elevator.querySelector('a[data-name="topic"]').classList.add('active');
    }
  });
})();